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Roll Your Own Da Vinci Style Worm Gear 



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Roll Your Own Da Vinci Style 

Worm Gear 

Written By: Alan Federman 



SUMMARY 

Da Vinci used wooden gears in many of his mechanisms and drawings. I've already figured 
out how to use "cage" or "lantern" gears (Make Magazine, October 2010). For my next 
project I decided to explore making a wooden worm gear. I'll show you how I built it. 

I used a 1 "-diameter poplar dowel (a standard item at Home Depot and Furrow). I used 
SketchUp to draw the gear using an involute-gear program. I used W birch plywood to cut 
the mating spur gear. It has 60 teeth and is 10" in diameter. You need two measurements to 
lay out the worm: 1) the "pitch" is the tooth-to-tooth distance of the spur gear, about Vz. 2) 
The other measurement is the outside circumference of the cylinder from which the worm 
gear will be cut (3.14"). 

To lay out the worm, draw a right triangle on a 17" by 11" piece of paper. For each 
circumference, go up one pitch. You should end up with a long narrow triangle. Cut this out 
carefully and wrap it around a 6" length of the dowel. (Depending on how you wrap the 
screw, it will be left- or right-handed.) Using tacky glue, hot glue or tape, fasten the paper to 
the dowel. I used a pencil to mark the edge of the paper. 

Next, I used a small fine-tooth Japanese-style pull saw to cut a W groove all along the line. 

After getting the first cut done, I carefully expanded the cut by cutting down from each side 
in a "V" pattern. I finished up with a triangular file and sandpaper. In the old days, large 



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Roll Your Own Da Vinci Style Worm Gear 

screws for wine- and cider presses were carved entirely using hammer and chisel. Once the 
screw was cut, a tap was made from it, and that was used to make the nuts. I plan to write 
another article about making wooden screws and nuts later. 

I used dowels and glue to attach all the parts. The supports are recycled oak from a kitchen 
remodel project and a couple of other scraps. 

The Da Vinci worm gear works well. The worm gear offers a large mechanical advantage. 
Each full turn of the crank moves the gear wheel one tooth; a 60-to-1 advantage. I hope to 
utilize both worm and lantern gears in my next Da Vinci project. 



Step 1 — Roll Your Own Da Vinci Style Worm Gear 

• Layout is important. 




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Roll Your Own Da Vinci Style Worm Gear 



Step 2 




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• Guide wrapped around dowel. 



V 



Step 3 




• Cutting out worm. 



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Roll Your Own Da Vinci Style Worm Gear 



Step 4 




• Final assembled project. 



This document was last generated on 2012-11-03 01 :11:51 AM. 



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